【作者】 汤燕娜；

【导师】 王文卿；

【作者基本信息】 厦门大学 ， 生态学， 2008， 硕士

【摘要】 胎生与红树植物有着非常密切的关系,一般认为胎生是红树植物对潮间带盐生环境的适应。但是,非胎生红树植物的广泛存在,使这个观点颇受争议。本工作研究了5种典型的非胎生海桑属红树植物的繁殖体发育过程,比较了非胎生与胎生红树植物繁殖体发育过程的区别。同时,探讨了繁殖体发育特征与海桑属红树植物在潮间带滩涂分布格局的关系。结果表明:1.非胎生海桑属红树植物与胎生红树植物在繁殖体发育过程方面表现出一些共性。(1)在繁殖体发育的整个过程,含水量都保持较高的水平。(2)与胎生红树及大部分红树植物一样,海桑属红树植物的成熟果实的密度接近或小于海水,适于漂浮传播。(3)随着果实的逐渐发育成熟,果实中五种矿质元素(Cl、Na、K、Ca、Mg)的干重含量逐步降低,表现出低盐化的过程。而且,果实Cl、Na、Ca和Mg等元素的含量远低于成熟叶片和花萼。组织液的元素浓度也呈现出下降的趋势。繁殖体发育过程是一个积累盐分的过程,单个果实各元素以及五种元素的总量均表现为上升的趋势。(4)虽然海桑属红树植物成熟果实中的无机渗透调节物质的总贡献率小于显胎生红树植物,但是杯萼海桑和卵叶海桑的成熟果实中无机渗透调节物质的总贡献率却大于隐胎生红树植物。结论:从以上几个方面,可以看出,非胎生与胎生红树植物之间并不存在显著差异,研究结果不支持胎生是红树植物对高盐生境的适应这种观点,关于胎生的意义,需要进一步考量。2.大量的因素影响了红树植物的分布格局。繁殖体发育特征与海桑属红树植物的分布有着密切联系。(1)五种海桑属红树植物成熟果的密度大小顺序为:杯萼海桑＞海桑、拟海桑＞海南海桑＞卵叶海桑,杯萼海桑成熟果的密度最高,而卵叶海桑最低。(2)比较了这五个种的成熟果实的Na/K比率,其大小关系为:杯萼海桑＞拟海桑、海南海桑＞卵叶海桑＞海桑。同时,比较了成熟叶片的Na/K比率,它们的大小关系为:杯萼海桑＞海南海桑、卵叶海桑＞拟海桑、海桑。结论:海桑属红树植物在潮间带的分布与它们的成熟果的密度有关系。密度大的,分布在低潮带;密度小的,分布在高潮带。而在有淡水注入的河口地形中,红树植物沿河的分布与红树植物的耐盐能力有关。红树植物的扩散包括了繁殖体传播阶段和定植生长阶段,我们提出一个假说:在繁殖体传播阶段,密度是影响红树植物分布的关键因素;而在定植生长阶段,红树植物的耐盐能力是决定其是否成活的重要因素之一,最终在一定程度上影响了红树植物的分布格局。更多还原

【Abstract】 Vivipary is so strongly associated with mangroves that it is suggested to have adaptive significance in the intertidal saline environment.But the existence of nonviviparous mangroves makes it suspicious.Developmental process of propagules of five species from nonviviparous mangroves Sonneratia was studied,which was compared with viviparous mangroves as well.At the same time,the relation between propagule traits and distribution of Sonneratia in intertidal zone was discussed.The results indicated:1.There was commonness in propagules development between Sonneratia and viviparous mangroves.(1) High water content was both maintained throughout development in viviparous mangroves and Sonneratia.(2) Density of mature fruits was close to or lower than seawater,thus the propagules can float.(3) The dynamics of the elements on a dry weight basis in the fruits indicated a desalinating process.Moreover,the content of C1,Na,Ca or Mg was lower in fruits than those in the mature leaves and calyx.Elements concentrations also show the trend of decreasing.(4) The contribution of inorganic osmotica in mature propagules was less than true vivipary,but was more than cryptovivipary.Conclusion:Comparing these results with others’ research about viviparous mangroves, distinct differences were not found.The hypothesis that vivipary among mangroves is an adaptation to salinity was not well supported.The value of vivipary should be reconsidered.2.Numerous factors influence distribution pattern of mangroves.There was close connection between propagule traits and distribution of Sonneratia.(1) The rank order of density of mature fruits was:S.alba＞S.caseolaris,S.× gulngai＞S.×hainanensis＞S.ovata.(2) The rank order of Na/K ratio of mature fruits was:S.alba＞S.×gulngai,S.×hainanensis＞S.ovata＞S.caseolaris.The rank order of Na/K ratio of mature leaves was:S.alba＞S.xhainanensis,S.ovata＞S.×gulngai,S. caseolaris.Conclusion:Mangrove distribution in intertidal zone may be related to density of propagules.Species whose adults are found on the landward edge of the intertidal zone,have propagules of small density;species whose adults are found on the seaward edge of the swamp,have propagules of large density.In the estuary which is affected by fresh water,distribution of mangrove species along estuaries has been shown to be related to salinity tolerance.Proliferate of mangrvoes includes stage of propagules dispersal and colonization.A hypothesis is proposed that density is key factor which impacts the distribution of mangroves in the stage of propagules dispersal.In the stage of colonization,the ability of salt tolerance of mangroves is one of important factors which decide whether propagules survive or not and eventually affect the distribution of mangrvoes to some extent.更多还原